The bulletins page contains a Documents Module where you will upload your bulletin.

Hover over the pencil icon, and select 'Add New Document'.

Give your bulletin a Title.

Scroll down to 'File Location' and through the drop down navigate to and select CMAdmin/Bulletins, then choose the 'Upload New File' button.

*When you click the Upload New File button, the buttons will change

Select the 'Choose File' button and navigate to the bulletin file that you want to upload, then click 'Upload Selected File', or you could choose 'Select An Existing File'.  

Select the 'Open Link in New Browser Window' checkbox so that when your users select the bulletin they don't navigate away from your website, then select 'Update'.